The two halves of the human brain are specialized for processing information in different ways, frequently described as analytic, for the left, and holistic, for the right. Is this characteristic uniquely human, perhaps related to our exceptional abilities in language and thought or can precursors be found in other animals? The proposed experiments examine the behavior of monkeys to see if their brains are lateralized in ways similar to those of human beings. To accomplish this, the two cerebral hemispheres of the brain are first surgically separated so that the cognitive functions of the two sides are isolated from each other. Then a series of tests is given to each side to determine their relative abilities at solving problems. The problems are selected to represent abilities specialized for either the right or left hemisphere of people. A finding of lateralized functions in animal would significantly aid our investigations of the mechanisms of hemispheric specialization in man and how they develop. It would also provide an experimental preparation for critically examining theories of individual differences, learning disability, and psychological abnormality, that propose a biological explanation based on unusual patterns of lateralization.